Method for utilizing at least one storage space sharing scheme to manage storage spaces utilized by video playback operation and related video playback apparatus thereof

ABSTRACT

An exemplary method for managing a first storage space and a second storage space utilized by a video playback operation includes: during a first time period, accessing the first storage space for data associated with a first processing operation included in the video playback operation, and accessing the second storage space for data associated with a second processing operation included in the video playback operation; and during a second time period, accessing the first storage space and the second storage space for data associated with the first processing operation. The first processing operation is different from the second processing operation. The second storage space is dedicated to buffering data associated with the second processing operation during the first time period.

BACKGROUND

The disclosed embodiments of the present invention relate to processingdata for video playback, and more particularly, to a method forutilizing one or more storage space sharing schemes to manage storagespaces utilized by a video playback operation and related video playbackapparatus thereof.

In regard to video playback, data buffers are generally required tostore processed data and/or unprocessed data. Taking the playback ofvideo contents provided by a Blu-ray disc (BD) for example, the dataread from the BD may include a primary video stream, secondary videostream, and background image data such as joint photographic expertsgroup (JPEG) files. If one dedicated frame buffer is particularlyallocated to buffer a decoding result of the primary video stream,another dedicated frame buffer is particularly allocated to buffer adecoding result of the secondary video stream, and one dedicated imagebuffer is particularly allocated to buffer a decoding result of thebackground image data, a huge storage space within a storage device(e.g., a memory) is occupied due to these buffers. In addition, thesebuffers should be properly managed to avoid the undesired memoryfragment and bandwidth problem.

Therefore, there is a need for an innovative buffer management schemewhich can effectively reduce the buffer requirement without degradingthe display quality.

SUMMARY

In accordance with exemplary embodiments of the present invention, amethod for utilizing one or more storage space sharing schemes to managestorage spaces utilized by a video playback operation and related videoplayback apparatus thereof are proposed to solve the above-mentionedproblem.

According to a first aspect of the present invention, an exemplarymethod for managing a first storage space and a second storage spaceutilized by a video playback operation is disclosed. The exemplarymethod includes the following steps: during a first time period,accessing the first storage space for data associated with a firstprocessing operation included in the video playback operation, andaccessing the second storage space for data associated with a secondprocessing operation included in the video playback operation, where thefirst processing operation is different from the second processingoperation, and the second storage space is dedicated to buffering dataassociated with the second processing operation during the first timeperiod; and during a second time period different from the first timeperiod, accessing the first storage space and the second storage spacefor data associated with the first processing operation.

According to a second aspect of the present invention, an exemplaryvideo playback apparatus is disclosed. The exemplary video playbackapparatus includes a storage device and a video playback processingdevice. The storage device has a first storage space and a secondstorage space allocated therein. During a first time period, the videoplayback processing device accesses the first storage space for dataassociated with a first processing operation performed by the videoplayback processing device, and accesses the second storage space fordata associated with a second processing operation performed by thevideo playback processing device, where the first processing operationis different from the second processing operation, and the secondstorage space is dedicated to buffering data associated with the secondprocessing operation during the first time period. During a second timeperiod different from the first time period, the video playbackprocessing device accesses the first storage space and the secondstorage space for data associated with the first processing operationperformed by the video playback processing device.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a video playback apparatusaccording to an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating a first exemplary storage space sharingscheme which may be employed by the video playback apparatus shown inFIG. 1.

FIG. 3 is a diagram illustrating a second exemplary storage spacesharing scheme which may be employed by the video playback apparatusshown in FIG. 1.

FIG. 4 is a diagram illustrating a third exemplary storage space sharingscheme which may be employed by the video playback apparatus shown inFIG. 1.

FIG. 5 is a diagram illustrating a first exemplary output presentation.

FIG. 6 is a diagram illustrating a first allocation layout of thestorage device shown in FIG. 1.

FIG. 7 is a diagram illustrating a second exemplary output presentation.

FIG. 8 is a diagram illustrating a second allocation layout of thestorage device shown in FIG. 1.

FIG. 9 is a diagram illustrating a third exemplary output presentation.

FIG. 10 is a diagram illustrating a third allocation layout of thestorage device shown in FIG. 1.

FIG. 11 is a diagram illustrating an alternative design of the storagedevice allocation layout shown in FIG. 10.

DETAILED DESCRIPTION

Certain terms are used throughout the description and following claimsto refer to particular components. As one skilled in the art willappreciate, manufacturers may refer to a component by different names.This document does not intend to distinguish between components thatdiffer in name but not function. In the following description and in theclaims, the terms “include” and “comprise” are used in an open-endedfashion, and thus should be interpreted to mean “include, but notlimited to . . . ”. Also, the term “couple” is intended to mean eitheran indirect or direct electrical connection. Accordingly, if one deviceis coupled to another device, that connection may be through a directelectrical connection, or through an indirect electrical connection viaother devices and connections.

Picture-in-picture (PiP) is a feature for displaying a secondary videoand a primary video at the same time, where the secondary video overlaysa partial area of the primary video. In accordance with the Blu-ray disc(BD) specification, no PiP function is supported when the primary videois scaled or a particular hardware configuration is set. Therefore, thesecondary video related buffer is available for other purposes undersuch a scenario. In addition, when the PiP function is enabled, abackground image is invisible and no background image change ispermitted according to the BD specification. Thus, part of thebackground image related buffer may be used for other purposes undersuch a scenario. Based on at least these observations, the storage spacesharing becomes feasible.

The conception of the present invention is to employ at least onestorage space sharing scheme to thereby effectively reduce the totalbuffer size of the implemented buffers. More specifically, a specificstorage space allocated in a storage device (e.g., a memory device) maybe shared between different processing operations included in a videoplayback operation. For example, during a first time period, a videoplayback processing device accesses a first storage space for dataassociated with a first processing operation performed by the videoplayback processing device, and accesses a second storage space for dataassociated with a second processing operation performed by the videoplayback processing device, wherein the first processing operation isdifferent from the second processing operation. However, during a secondtime period different from the first time period, the video playbackprocessing device accesses the first storage space and the secondstorage space for data associated with the first processing operationperformed by the video playback processing device, wherein the secondstorage space is dedicated to buffering data associated with the secondprocessing operation during the first time period. In one exemplarystorage space sharing scheme, the first processing operation may be avideo output operation, and the second processing operation may be avideo decoding operation. In another exemplary storage space sharingscheme, the first processing operation may be a non-scaled video outputoperation, and the second processing operation may be a scaled videooutput operation. In yet another exemplary storage space sharing scheme,the first processing operation may be a still image decoding operation,and the second processing operation may be a video decoding operation.Further details are described as follows.

Please refer to FIG. 1, which is a block diagram illustrating a videoplayback apparatus 100 according to an exemplary embodiment of thepresent invention. The exemplary video playback apparatus 100 includes avideo playback processing device 102 and a storage device 104. The videoplayback processing device 102 includes a video decoding circuit 106, astill image decoding circuit 108, and a video output circuit 110,wherein the video decoding circuit 106 includes a plurality of videodecoders 112_1 and 112_2. The video output circuit 110 includes aplurality of display modules 114_1-114_3 and a plane mixer 116. By wayof example, but not limitation, the video playback apparatus 100 may beimplemented in a BD player used to perform a video playback operationupon video contents recorded on a Blu-ray disc according to the BDspecification. Therefore, a primary video stream V_PRI and a secondaryvideo stream V_SEC complying with the BD specification are fed into thevideo decoding circuit 106, and a background image data IMG_BG complyingwith the BD specification is fed into the still image decoding circuit108. For example, the background image data IMG_BG is encoded/compressedusing a joint photographic experts group (JPEG) standard, and the stillimage decoding circuit 108 may be realized by a JPEG decoder. However,this is for illustrative purposes only, and is not meant to be taken asa limitation of the present invention.

In this exemplary embodiment, one video decoder 112_1 in the videodecoding circuit 106 is dedicated to decoding the incoming primary videostream V_PRI, and another video decoder 112_2 in the video decodingcircuit 106 is dedicated to decoding the incoming secondary video streamV_SEC. However, in an alternative design, the video decoding circuit 106may be modified to have one decoder included therein for decoding bothof the primary video stream V_PRI and the secondary video stream V_SEC.

The storage device 104 may be implemented using one or more storageelements to have a plurality of storage spaces allocated therein forbuffering the decoded results generated from the preceding videodecoding circuit 106 and the still image decoding circuit 108. Forexample, the storage device 104 is a memory device (e.g., a dynamicrandom access memory) with frame buffer(s) allocated therein for thevideo decoder(s) included in the video decoding circuit 106 and abackground image buffer allocated therein for the still image decodingcircuit (e.g., a JPEG decoder) 108.

The video output circuit 110 is arranged to read the decoded video/imagedata buffered in the storage device 104 and generate a video outputS_OUT to a display device such as a television. For example, in a casewhere the decoded video data includes fields, the video output circuit110 may perform de-interlacing upon the fields and accordingly generateframes to be displayed. As shown in FIG. 1, the display module 114_1 isarranged to read decoded video data derived from the primary videostream V_PRI and generate a primary video output to the plane mixer 116,the display module 114_2 is arranged to read decoded video data derivedfrom the secondary video stream V_SEC and generate a secondary videooutput to the plane mixer 116, and the display module 114_3 is arrangedto read decoded images derived from the background image data IMG_BG andgenerate a background image output to the plane mixer 116. As mentionedabove, the display modules 114_1 and 114_2 may have the de-interlacingcapability for generating the primary video output and secondary videooutput according to fields generated from the video decoding circuit106. The plane mixer 116 is use to properly mix the primary videooutput, the secondary video output and/or the background image videooutput and accordingly generate the video output S_OUT which carries thedesired video contents to be displayed on the display device. As thepresent invention focuses on the management of storage spaces allocatedin the storage device 104, further description directed to theoperations and functions of the video decoding circuit 106, the stillimage decoding circuit 108, and the video output circuit 110 is omittedhere for the sake of brevity.

Please refer to FIG. 2, which is a diagram illustrating a firstexemplary storage space sharing scheme which may be employed by thevideo playback apparatus 100. In this exemplary embodiment, the storagedevice 104 shown in FIG. 1 has a plurality of allocated storage spaces,including a first storage space 202, a second storage space 204, and athird storage space 206. Consider a situation where each of the displaymodules 114_1 and 114_2 employs a 4-field de-interlacing scheme togenerate one frame by referring to four fields, and each of the videodecoders 112_1 and 112_2 generates one decoded predictive picture(P-picture) or bi-predictive picture (B-picture) by referring to aplurality of reference pictures. Regarding the decoding of aP-picture/B-picture for the primary video which has a high-definition(HD) resolution, a maximum number of the reference pictures is fouraccording to the BD specification. Regarding the decoding of aP-picture/B-picture for the secondary video which has astandard-definition (SD) resolution, a maximum number of the referencepictures is five according to the BD specification. As can be seen fromFIG. 2, the first storage device 202 includes two display buffers 211and 212 each for buffering two pictures, such as one top field F_0/F_1and one bottom field f_0/f_1 to be read and processed by the displaymodule 114_1/114_2; the second storage space 204 includes one decodingbuffer 213 for buffering decoded data currently generated from the videodecoder 112_1/112_2; and the third storage space 206 is used to buffer aplurality of reference pictures Ref_1-Ref_N referred to by the videodecoder 112_1/112_2 for generating the decoded data to the decodingbuffer 213.

Please note that the second storage space 204 includes a first bufferarea 214 and a second buffer area 215. When the video playback apparatus100 is operated under a first phase of a display mode, the secondstorage space 204 is dedicated to buffering decoded data generated fromthe video decoder 112_1/112_2, and the first storage space 202 isdedicated to storing data to be read and processed by the display module114_1/114_2, as shown in the sub-diagram (A) of FIG. 2. Thus, the videodecoder 112_1/112_2 of the video decoding circuit 106 generates aportion of a first picture (e.g., a portion F_21 of a top field F_2) anda portion of a second picture (e.g., a portion f_21 of a bottom fieldf_2) to the second buffer area 214 and the second buffer area 215,respectively, and the display module 114_1/114_2 of the video outputcircuit 110 reads data from the first storage space 202 for furtherprocessing. For example, the display module 114_1/114_2 may perform a4-field de-interlacing operation upon four fields such as top fields F_0and F_1 and bottom fields f_0 and f_1, wherein the top field F_0, thebottom field f_0, the top field F_1, and the bottom field f_1 aretemporally successive fields.

When the video playback apparatus 100 is operated under a second phaseof the display mode, the video decoder 112_1/112_2 of the video decodingcircuit 106 respectively generates a remaining portion of the firstpicture (e.g., a remaining portion F_22 of the top field F_2) and aremaining portion of the second picture (e.g., a remaining portion f_22of the bottom field f_2) to the first buffer area 214 and the secondbuffer area 215, as shown in the sub-diagram (B) of FIG. 2. In addition,the display module 114_1/114_2 of the video output circuit 110 readsdata from the first storage space 202 and also sequentially reads theportion and the remaining portion of the first picture (e.g., F_21 andF_22) from the first buffer area 214. That is, the display module114_1/114_2 performs a 4-field de-interlacing operation upon four fieldssuch as top fields F_2 and F_1 and bottom fields f_1 and f_0, whereinthe bottom field f_0, the top field F_1, the bottom field f_1, and thetop field F_2 are temporally successive fields. It should be noted thatthe video decoder 112_1/112_2 sequentially stores data of the remainingportion of the first picture (e.g., the remaining portion F_22 of thetop field F_2) into the first buffer area 214 while the display module114_1/114_2 is sequentially reading data of the portion of the firstpicture (e.g., the portion F_21 of the top field F_2) from the firstbuffer area 214; however, the video decoder 112_1/112_2 finishes storingthe remaining portion of the first picture (e.g., the remaining portionF_22 of the top field F_2) into the first buffer area 214 before thedisplay module 114_1/114_2 finishes reading the portion and theremaining portion of the first picture (e.g., F_21 and F_22) from thefirst buffer area 214. Thus, the second storage space 204 can besuccessfully shared between a first processing operation (e.g., a videooutput operation) and a second processing operation (e.g., a videodecoding operation) performed by the video playback apparatus 100.

The first exemplary storage space sharing scheme can be brieflysummarized as follows. During a first time period in which the videoplayback apparatus 100 is operated under a first phase of a displaymode, the display module 114_1/114_2 of the video output circuit 110accesses the first storage space 202 for data associated with a firstprocessing operation (e.g., a video output operation), and the videodecoder 112_1/112_2 of the video decoding circuit 106 accesses thesecond storage space 204 for data associated with a second processingoperation (e.g., a video decoding operation). In addition, during asecond time period in which the video playback apparatus 100 is operatedunder a second phase of the display mode, the display module 114_1/114_2of the video output circuit 110 accesses the first storage space 202 andthe second storage space 204 for data associated with the firstprocessing operation, wherein the second storage space 204 is dedicatedto buffering data associated with the second processing operation duringthe first time period.

Please refer to FIG. 3, which is a diagram illustrating a secondexemplary storage space sharing scheme which may be employed by thevideo playback apparatus 100. In this exemplary embodiment, the storagedevice 104 shown in FIG. 1 has a plurality of allocated storage spaces,including a first storage space 302 and a second storage space 304.Consider a situation where each of the display modules 114_1 and 114_2employs a 4-field de-interlacing scheme to process four non-scaledfields and accordingly generate at least one non-scaled frame when anon-scaled video output of the primary/secondary video is requested; inaddition, each of the video decoders 112_1 and 112_2 generates scaledfields and each of the display modules 114_1 and 114_2 performs the4-field de-interlacing operation upon four scaled fields to generate atleast one scaled frame when a scaled video output of theprimary/secondary video is requested. For example, when a downscaledvideo output of the primary/secondary video is requested, each of thevideo decoders 112_1 and 112_2 generates downscaled fields and each ofthe display modules 114_1 and 114_2 performs de-interlacing upon thedownscaled fields to generate downscaled frames to be displayed. Itshould be noted that in accordance with the BD specification, thenon-scaled video output of the primary/secondary video is disabled whenthe scaled video output of the primary/secondary video is enabled. Toput it another way, the display buffers originally used for bufferingthe non-scaled fields are not used for actual video playback when thescaled video playback is enabled. Thus, the display buffers may be usedfor buffering scaled fields required by the scaled video playback.However, it is possible that a zoom change function is activated by theuser to show the non-scaled video contents during the scaled videoplayback. In one exemplary design of the present invention, only part ofthe display buffers is used for buffering the scaled fields after thescaled video playback is enabled, and the remaining display buffers areused for buffering non-scaled fields in case a zoom change function isactivated during the scaled video playback. In this way, the displayquality is not degraded even though the storage space sharing scheme isemployed.

When the video playback apparatus 100 is operated under one displaymode, the first storage space 302 is configured to have two displaybuffers 311 and 312 allocated therein, and the second storage space 304is configured to have a display buffer 313 allocated therein, whereineach of the display buffers 311-313 is used for buffering two non-scaledpictures, such as one top field F_0/F_1/F_2 and one bottom fieldf_0/f_1/f_2 shown in the sub-diagram (A) of FIG. 3. The display module114_1/114_2 of the video output circuit 110 may perform a 4-fieldde-interlacing operation according to four temporally successive fieldsstored in the first storage space 302 and the second storage space 304.For example, the top field F_0, the bottom field f_0, the top field F_1,and the bottom field f_1 are read from the display buffers 312 and 313by the display module 114_1/114_2, or the bottom field f_0, the topfield F_1, the bottom field f_1, and the top field F_2 are read from thedisplay buffers 311-313 by the display module 114_1/114_2.

When the video playback apparatus 100 is operated under another displaymode, the first storage space 302 is configured to have two displaybuffers 311 and 312 allocated therein, but the second storage space 304is configured to have a plurality of scale buffers allocated therein, asshown in the sub-diagram (B) of FIG. 3. In accordance with the BDspecification, five downscale buffers may be required by the scaledvideo output of the primary/secondary video. As can be seen from thefigure, the second storage space 304 may be configured to have fivescale buffers (e.g., downscale buffers) 314_1-314_5 dedicated tobuffering data of scaled pictures (e.g., scaled fields) required by thescaled video playback, wherein the scale buffers 314_1-314_3 may act asdisplay buffers used for buffering scaled fields (e.g., scaled topfields F_0′, F_1′, and F_2′ and scaled bottom fields f_0′, f_1′, andf_2′) to be read and processed by the display module 114_1/114_2 whichemploys a 4-field de-interlacing scheme, the scale buffer 314_5 may actas a decoding buffer for buffering any decoded data currently generatedfrom the video decoder 112_1/112_2, and the scale buffer 314_4 may actas a buffer for buffering a decoded but not yet displayed picture orbuffering a scaled picture. Thus, the second storage space 304 can besuccessfully shared between a first processing operation (e.g., anon-scaled video decoding operation) and a second processing operation(e.g., a scaled video decoding operation) performed by the videoplayback apparatus 100.

The second exemplary storage space sharing scheme can be brieflysummarized as follows. During a first time period in which the videoplayback apparatus 100 is operated under a first display mode, the videodecoder 112_1/112_2 of the video decoding circuit 106 accesses the firststorage space 302 for data associated with a first processing operation(e.g., a non-scaled video output operation) and accesses the secondstorage space 304 for data associated with a second processing operation(e.g., a scaled video decoding operation). In addition, during a secondtime period in which the video playback apparatus 100 is operated undera second display mode different from the first display mode, the videodecoder 112_1/112_2 of the video decoding circuit 106 accesses the firststorage space 302 and the second storage space 304 for data associatedwith the first processing operation, wherein the second storage space304 is dedicated to buffering data associated with the second processingoperation during the first time period in which the video playbackapparatus 100 is operated under the first display mode.

Please refer to FIG. 4, which is a diagram illustrating a thirdexemplary storage space sharing scheme which may be employed by thevideo playback apparatus 100. In this exemplary embodiment, the storagedevice 104 shown in FIG. 1 has a plurality of allocated storage spaces,including a first storage space 402 and a second storage space 404. Ingeneral, two background image buffers, respectively used to buffer twobackground images, are employed to avoid the undesired tearing effect.That is, one of the background image buffers acts as a working bufferfor a background image which is currently generated from decoding thebackground image data, whereas the other the background image buffersstores a background image which has been derived from decoding thebackground image data. However, as mentioned above, no background imagechange is permitted and the background image is invisible during the PiPplayback. Thus, one of the background image buffers may be used forother purposes. For example, when the PiP function is enabled, onebackground image buffer is used to keep a background image, and theother background image buffer may be configured to buffer data of thesecondary video.

When the video playback apparatus 100 is operated under one displaymode, the first storage space 402 is configured to have a backgroundimage buffer 411 allocated therein for buffering one background imageIMG_1 and the second storage space 404 is configured to have abackground image buffer 412 allocated therein for buffering onebackground image IMG_2, as shown in the sub-diagram (A) of FIG. 4. Forexample, the background image buffer 412 serves as a working buffer forstore decoded data currently generated from the still image decodingcircuit 108. Therefore, the background image IMG_2 is generated afterthe complete background image IMG_1 is derived and stored in thebackground image buffer 411. When the video playback apparatus 100 isoperated under another display mode, the first storage space 402 isconfigured to have the background image buffer 411 for keeping thelatest background image IMG and the second storage space 404 isconfigured to have a plurality of buffers dedicated to buffering thesecondary video related data, as shown in the sub-diagram (B) of FIG. 4.Regarding the decoding of a P-picture/B-picture of the secondary videowhich has an SD resolution, a maximum number of the reference picturesis five according to the BD specification. Therefore, in this exemplaryembodiment, five reference buffers 413_1-413_5 may be allocated in thesecond storage space 404. In addition, one decoding buffer 414 forbuffering the decoded data currently generated from the video decoder112_2, three display buffers 415_1-415_3 for buffering fields to be readand processed by the display module 114_2, and a plurality of scalebuffers (e.g., downscale buffers) 416_1-416_5 are also allocated in thesecond storage space 404. Thus, the second storage space 404 can besuccessfully shared between a first processing operation (e.g., a stillimage decoding operation) and a second processing operation (e.g., avideo decoding operation) performed by the video playback apparatus 100.

The third exemplary storage space sharing scheme can be brieflysummarized as follows. During a first time period in which the videoplayback apparatus 100 is operated under a first display mode, the stillimage decoding circuit 108 of the video decoding circuit 106 accessesthe first storage space 402 for data associated with a first processingoperation (e.g., a still image decoding operation), and the videodecoder 112_2 of the video decoding circuit 106 accesses the secondstorage space 404 for data associated with a second processing operation(e.g., a video decoding operation). In addition, during a second timeperiod in which the video playback apparatus 100 is operated under asecond display mode different from the first display mode, the stillimage decoding circuit 108 of the video decoding circuit 106 accessesthe first storage space 402 and the second storage space 404 for dataassociated with the first processing operation, wherein the secondstorage space 404 is dedicated to buffering data associated with thesecond processing operation during the first time period in which thevideo playback apparatus 100 is operated under the first display mode.

In the following, several exemplary output presentations and thepertinent allocation layouts of the storage device 104 are provided forbetter understanding of technical features of the present invention.

Please refer to FIG. 5 in conjunction with FIG. 6. FIG. 5 is a diagramillustrating a first exemplary output presentation under a specificdisplay mode, and FIG. 6 is a diagram illustrating a first allocationlayout of the storage device 104 which corresponds to the exemplaryoutput presentation shown in FIG. 5. Regarding the first exemplaryoutput presentation shown in FIG. 5, the primary video is not downscaledand therefore has a resolution of 1920×1080, the secondary video isdownscaled and therefore has a resolution of 640×480, and a backgroundimage is on the background and not displayed. The primary video framebuffer 602 is configured to have 7 allocated buffers, including 4buffers acting as reference (“REF”) buffers, one buffer acting as adecoding and display (DEC & DISP) buffer, and two buffers acting asdisplay (“DISP”) buffers. It should be noted that as the scaled primaryvideo playback (e.g., downscaled primary video playback) is not enabled,the primary video frame buffer 602 does not need scale buffers (e.g.,downscale buffers) included therein. Regarding the secondary video framebuffer 604, it has 12 allocated buffers, including 5 buffers acting asreference (“REF”) buffers, one buffer acting as a decoding and display(DEC & DISP) buffer, one buffer acting as a display (“DISP”) buffer, and5 smaller buffers acting as downscale (“DS”) buffers. As shown in FIG.6, a size of one reference buffer included in the primary video framebuffer 602 is equal to a total size of 5 reference buffers included inthe secondary video frame buffer 604, and a size of one reference bufferincluded in the secondary video frame buffer 604 is equal to a totalsize of 5 downscale buffers included in the secondary video frame buffer604. Regarding the background image buffer 606, it has one allocatedimage (“B_IMG”) buffer. Suppose that each buffer with a size equal tothat of a reference buffer included in the primary video frame buffer602 has a storage capacity of 3M bytes, and each buffer with a sizeequal to that of a reference buffer included in the secondary videoframe buffer 604 has a storage capacity of 600K bytes. As the firststorage space sharing scheme is applied to the primary video framebuffer 602, the implementation of the primary video frame buffer 602requires a total storage capacity of 21M (7*3M) bytes. As the firststorage space sharing scheme and the second storage space sharing schemeare both applied to the secondary video frame buffer 604, theimplementation of the secondary video frame buffer 604 requires a totalstorage capacity of 4.8M (7*600K+5*120K (i.e., 1*600K)) bytes. Inaddition, the implementation of the background image buffer 606 simplyrequires a total storage capacity of 3M (1*3M) bytes.

Please refer to FIG. 7 in conjunction with FIG. 8. FIG. 7 is a diagramillustrating a second exemplary output presentation under a specificdisplay mode, and FIG. 8 is a diagram illustrating a second allocationlayout of the storage device 104 which corresponds to the exemplaryoutput presentation shown in FIG. 7. Regarding the second exemplaryoutput presentation shown in FIG. 7, the primary video is downscaled andhas a resolution of 720×480, the secondary video is downscaled and has aresolution of 244×214, and a background image is on the background andnot displayed. The primary video frame buffer 702 has 7 allocatedbuffers, including 4 buffers acting as reference (“REF”) buffers, onebuffer acting as a decoding and display (DEC & DISP) buffer, one bufferacting as a display (“DISP”) buffer, and five smaller buffers acting asdownscale (“DS”) buffers. It should be noted that as the scaled primaryvideo playback (e.g., downscaled primary video playback) is enabled, theprimary video frame buffer 702 therefore needs scale buffers (e.g.,downscale buffers) included therein. Regarding the secondary video framebuffer 704, it has 12 allocated buffers, including 5 buffers acting asreference (“REF”) buffers, one buffer acting as a decoding and display(DEC & DISP) buffer, one buffer acting as a display (“DISP”) buffer, and5 smaller buffers acting as downscale (“DS”) buffers. As shown in FIG.8, a size of one reference buffer included in the primary video framebuffer 702 is equal to a total size of 5 reference buffers included inthe secondary video frame buffer 704, a size of one reference bufferincluded in the secondary video frame buffer 704 is equal to a totalsize of 5 downscale buffers included in the secondary video frame buffer704, and a size of one reference buffer included in the primary videoframe buffer 702 is equal to a total size of 5 downscale buffersincluded in the primary video frame buffer 702. Regarding the backgroundimage buffer 706, it has one allocated image (“B_IMG”) buffer. Supposethat each buffer with a size equal to that of a reference bufferincluded in the primary video frame buffer 702 has a storage capacity of3 M bytes, and each buffer with a size equal to that of a referencebuffer included in the secondary video frame buffer 704 has a storagecapacity of 600K bytes. As the first storage space sharing scheme andthe second storage space sharing scheme are both applied to the primaryvideo frame buffer 702, the implementation of the primary video framebuffer 702 therefore requires a total storage capacity of 21M(6*3M+5*600K (i.e., 1*3M)) bytes. As the first storage space sharingscheme and the second storage space sharing scheme are both applied tothe secondary video frame buffer 704, the implementation of thesecondary video frame buffer 704 therefore requires a total storagecapacity of 4.8M (7*600K+5*120K) bytes. In addition, the implementationof the background image buffer 706 simply requires a total storagecapacity of 3M (1*3M) bytes.

Please refer to FIG. 9 in conjunction with FIG. 10. FIG. 9 is a diagramillustrating a third exemplary output presentation under a specificdisplay mode, and FIG. 10 is a diagram illustrating a third allocationlayout of the storage device 104 which corresponds to the exemplaryoutput presentation shown in FIG. 9. Regarding the third exemplaryoutput presentation shown in FIG. 9, the primary video is downscaled andhas a resolution lower than 1920×1080, no secondary video is displayed,and a background image is on the foreground and displayed. The primaryvideo frame buffer 1002 has 12 allocated buffers, including 4 buffersacting as reference (“REF”) buffers, one buffer acting as a decoding anddisplay (DEC & DISP) buffer, two buffers acting as display (“DISP”)buffers, and five smaller buffers acting as downscale (“DS”) buffers. Itshould be noted that as scaled primary video playback (e.g., downscaledprimary video playback) is enabled, the primary video frame buffer 1002therefore needs scale buffers (e.g., downscale buffers) includedtherein. As shown in FIG. 10, a size of one reference buffer included inthe primary video frame buffer 1002 is equal to a total size of 5downscale buffers included in the primary video frame buffer 1002. As nosecondary video playback is needed, the secondary video frame buffer1004 can be configured to have one allocated buffer which acts as animage (“B_IMG”) buffer such as a working buffer for a background image.Regarding the background image buffer 1006, it has one allocated image(“B_IMG”) buffer. Suppose that each buffer with a size equal to that ofa reference buffer included in the primary video frame buffer 1002 has astorage capacity of 3M bytes. As the first storage space sharing schemeis applied to the primary video frame buffer 1002, the implementation ofthe primary video frame buffer 1002 therefore requires a total storagecapacity of 24M (7*3M+5*600K (i.e., 1*3M)) bytes. As the third storagespace sharing scheme is applied to the secondary video frame buffer1004, the implementation of the secondary video frame buffer 1004therefore requires a total storage capacity of 3M (1*3M) bytes. Inaddition, the implementation of the background image buffer 1006 simplyrequires a total storage capacity of 3M (1*3M) bytes.

Regarding the primary video frame buffer 1002 shown in FIG. 10, only thefirst storage space sharing scheme is applied thereto. However, in analternative design of the primary video frame buffer 1002 as shown inFIG. 11, the first storage space sharing scheme and the second storagespace sharing scheme are both applied to the primary video frame buffer1002′. Thus, the implementation of the primary video frame buffer 1002′requires a total storage capacity of 21M (6*3M+5*600K (i.e., 1*3M))bytes. Compared to the implementation of the primary video frame buffer1002 shown in FIG. 10, the implementation of the primary video framebuffer 1002′ occupies a smaller storage area.

To meet all buffer requirements of these exemplary output presentationsmentioned above, a minimum required storage capacity of the storagedevice 104 is 31.8M (24M+4.8M+3M). Thus, with the help of the proposedstorage space sharing schemes, the storage device 104 with a smallerstorage capacity can be realized, leading to a reduced production costof the video playback apparatus 100.

It should be noted that the exemplary allocation layouts of the storagedevice 104 shown in FIG. 6, FIG. 8, FIG. 10, and FIG. 11 are forillustrative purposes only, and are not meant to be limitations to thescope of the present invention. That is, any storage device allocationlayout employing at least one of the aforementioned exemplary storagespace sharing schemes shown in FIG. 2, FIG. 3, and FIG. 4 obeys thespirit of the present invention and falls with the scope of the presentinvention.

Moreover, in above exemplary embodiments, the primary video streamV_PRI, the secondary video stream V_SEC, and the background image dataIMG_BG are all derived from a BD disc and thus comply with the BDspecification. However, this by no means implies that the exemplarystorage space sharing schemes can be applied to the playback of BD videocontents only. That is, an exemplary storage space sharing schemeproposed in the present invention can be employed to reduce the bufferrequirement as long as the condition/criterion of performing theexemplary storage space sharing scheme is satisfied. In this way, thedisplay quality is not degraded even though the storage space sharingscheme is employed.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention.

What is claimed is:
 1. A method for managing a first storage space and asecond storage space utilized by a video playback operation, comprising:during a first time period, accessing the first storage space for dataassociated with a first processing operation included in the videoplayback operation, and accessing the second storage space for dataassociated with a second processing operation included in the videoplayback operation, wherein the first processing operation is differentfrom the second processing operation, and the second storage space isdedicated during the first time period to buffering data associated withthe second processing operation; and during a second time perioddifferent from the first time period, accessing the first storage spaceand the second storage space for data associated with the firstprocessing operation of the video playback operation; wherein the secondstorage space is different from the first storage space; and the secondstorage space is not accessed by the first processing operation of thevideo playback operation during the first time period, and is accessedby the first processing operation during the second time period.
 2. Themethod of claim 1, wherein during the first time period, the videoplayback operation is operated under a first phase of a display mode;during the second time period, the video playback operation is operatedunder a second phase of the display mode; the first processing operationis a video output operation; and the second processing operation is avideo decoding operation.
 3. The method of claim 2, wherein the videodecoding operation generates a plurality of fields, and the video outputoperation performs de-interlacing upon the fields and accordinglygenerates at least one frame.
 4. The method of claim 3, wherein thesecond storage space includes a first buffer area and a second bufferarea; when the video playback operation is operated under the firstphase of the display mode, the video decoding operation generates aportion of a first picture and a portion of a second picture to thefirst buffer area and the second buffer area, respectively, and thevideo output operation reads data from the first storage space, whereinone of the first picture and the second picture is a top field and theother of the first picture and the second picture is a bottom field; andwhen the video playback operation is operated under the second phase ofthe display mode, the video decoding operation generates a remainingportion of the first picture and a remaining portion of the secondpicture to the first buffer area and the second buffer area,respectively, and the video output operation reads data from the firststorage space and sequentially reads the portion and the remainingportion of the first picture from the first buffer area.
 5. The methodof claim 2, wherein the video output operation is a non-scaled videooutput operation which processes non-scaled pictures.
 6. The method ofclaim 2, wherein the video decoding operation decodes a primary videostream complying with a Blu-ray disc (BD) specification.
 7. The methodof claim 2, wherein the video decoding operation decodes a secondaryvideo stream complying with a Blu-ray disc (BD) specification.
 8. Themethod of claim 1, wherein during the first time period, the videoplayback operation is operated under a first display mode; during thesecond time period, the video playback operation is operated under asecond display mode different from the first display mode; the firstprocessing operation is a non-scaled video decoding operation whichgenerates non-scaled pictures; and the second processing operation is ascaled video decoding operation which generates scaled pictures.
 9. Themethod of claim 8, wherein when the video playback operation is operatedunder the second display mode, the first storage space is configured tohave a plurality of display buffers allocated therein and the secondstorage space is configured to have a display buffer allocated therein;when the video playback operation is operated under the first displaymode, the first storage space is configured to have the display buffersallocated therein and the second storage space is configured to have aplurality of scale buffers allocated therein; each allocated displaybuffer is for buffering non-scaled picture data; and each allocatedscale buffer is for buffering scaled picture data.
 10. The method ofclaim 8, wherein the non-scaled pictures and the scaled pictures arederived from a primary video stream complying with a Blu-ray disc (BD)specification.
 11. The method of claim 8, wherein the non-scaledpictures and the scaled pictures are derived from a secondary videostream complying with a Blu-ray disc (BD) specification.
 12. The methodof claim 1, wherein during the first time period, the video playbackoperation is operated under a first display mode; during the second timeperiod, the video playback operation is operated under a second displaymode different from the first display mode; the first processingoperation is a still image decoding operation; and the second processingoperation is a video decoding operation.
 13. The method of claim 12,wherein when the video playback operation is operated under the firstdisplay mode, a still image generated by the still image decodingoperation is kept in the first storage space during the first timeperiod, and the video decoding operation generates pictures to thesecond storage space; and when the video playback operation is operatedunder the second display mode, the still image decoding operationgenerates a first image to the first storage space, and generates asecond background image to the second storage space.
 14. The method ofclaim 12, wherein the video decoding operation decodes a secondary videostream complying with a Blu-ray disc (BD) specification, and the stillimage decoding operation decodes background image data complying withthe BD specification.
 15. A video playback apparatus, comprising: astorage device, having a first storage space and a second storage spaceallocated therein; and a video playback processing device, coupled tothe storage device, wherein during a first time period, the videoplayback processing device accesses the first storage space for dataassociated with a first processing operation performed by the videoplayback processing device, and accesses the second storage space fordata associated with a second processing operation performed by thevideo playback processing device, where the first processing operationis different from the second processing operation, and the secondstorage space is dedicated during the first time period to bufferingdata associated with the second processing operation; and during asecond time period different from the first time period, the videoplayback processing device accesses the first storage space and thesecond storage space for data associated with the first processingoperation of the video playback operation performed by the videoplayback processing device; wherein the second storage space isdifferent from the first storage space; and the second storage space isnot accessed by the first processing operation performed by the videoplayback processing device during the first time period, and is accessedby the first processing operation of the video playback operationperformed by the video playback processing device during the second timeperiod.
 16. The video playback apparatus of claim 15, wherein during thefirst time period, the video playback apparatus is operated under afirst phase of a display mode; during the second time period, the videoplayback apparatus is operated under a second phase of the display mode;and the video playback processing device comprises: a video outputcircuit, arranged to perform the first processing operation; and a videodecoding circuit, arranged to perform the second processing operation.17. The video playback apparatus of claim 16, wherein the video decodingcircuit generates a plurality of fields, and the video output circuitperforms de-interlacing upon the fields and accordingly generates atleast one frame.
 18. The video playback apparatus of claim 17, whereinthe second storage space includes a first buffer area and a secondbuffer area; when the video playback apparatus is operated under thefirst phase of the display mode, the video decoding circuit generates aportion of a first picture and a portion of a second picture to thefirst buffer area and the second buffer area, respectively, and thevideo output circuit reads data from the first storage space, where oneof the first picture and the second picture is a top field and the otherof the first picture and the second picture is a bottom field; and whenthe video playback apparatus is operated under the second phase of thedisplay mode, the video decoding circuit generates a remaining portionof the first picture and a remaining portion of the second picture tothe first buffer area and the second buffer area, respectively, and thevideo output circuit reads data from the first storage space andsequentially reads the portion and the remaining portion of the firstpicture from the first buffer area.
 19. The video playback apparatus ofclaim 16, wherein the first processing operation performed by the videooutput circuit is a non-scaled video output operation which processesnon-scaled pictures.
 20. The video playback apparatus of claim 16,wherein the video decoding circuit decodes a primary video streamcomplying with a Blu-ray disc (BD) specification.
 21. The video playbackapparatus of claim 16, wherein the video decoding circuit decodes asecondary video stream complying with a Blu-ray disc (BD) specification.22. The video playback apparatus of claim 15, wherein during the firsttime period, the video playback apparatus is operated under a firstdisplay mode; during the second time period, the video playbackapparatus is operated under a second display mode different from thefirst display mode; and the video playback processing device comprises:a video decoding circuit, arranged to perform the first processingoperation and the second processing operation, wherein the firstprocessing operation is a non-scaled video decoding operation whichgenerates non-scaled pictures, and the second processing operation is ascaled video decoding operation which generates scaled pictures.
 23. Thevideo playback apparatus of claim 22, wherein when the video playbackapparatus is operated under the second display mode, the first storagespace of the storage device is configured to have a plurality of displaybuffers allocated therein and the second storage space of the storagedevice is configured to have a display buffer allocated therein; whenthe video playback apparatus is operated under the first display mode,the first storage space of the storage device is configured to have thedisplay buffers allocated therein and the second storage space of thestorage device is configured to have a plurality of scale buffersallocated therein; each allocated display buffer is for bufferingnon-scaled picture data; and each allocated scale buffer is forbuffering scaled picture data.
 24. The video playback apparatus of claim22, wherein the non-scaled pictures and the scaled pictures are derivedfrom a primary video stream complying with a Blu-ray disc (BD)specification.
 25. The video playback apparatus of claim 22, wherein thenon-scaled pictures and the scaled pictures are derived from a secondaryvideo stream complying with a Blu-ray disc (BD) specification.
 26. Thevideo playback apparatus of claim 15, wherein during the first timeperiod, the video playback apparatus is operated under a first displaymode; during the second time period, the video playback apparatus isoperated under a second display mode different from the first displaymode; and the video playback processing device comprises: a still imagedecoding circuit, arranged to perform the first processing operation;and a video decoding circuit, arranged to perform the second processingoperation.
 27. The video playback apparatus of claim 26, wherein whenthe video playback apparatus is operated under the first display mode, astill image generated by the still image decoding circuit is kept in thefirst storage space during the first time period, and the video decodingcircuit generates pictures to the second storage space; and when thevideo playback apparatus is operated under the second display mode, thestill image decoding circuit generates a first image to the firststorage space, and generates a second background image to the secondstorage space.
 28. The video playback apparatus of claim 26, wherein thevideo decoding circuit decodes a secondary video stream complying with aBlu-ray disc (BD) specification, and the still image decoding circuitdecodes background image data complying with the BD specification.